By National Gardening Association Editors
When winter winds blow and the outdoor landscape no longer beckons, gardeners' thoughts turn to visions of African Violets, Hoyas, and other tropical plants. Fill your home with botanical life during the winter and beyond by creating an indoor garden oasis. Dracaenas, Norfolk Island pines, dwarf citrus trees, and ivies are just a few of the many plants that thrive indoors.
Whether you're growing gardenias or cultivating Christmas cacti, there are some basic rules of thumb for caring for houseplants.
How to Water Houseplants
Most houseplants require evenly moist, but not wet, soil. Saturate the soil with tepid water, preferably in the morning -- this allows inadvertently moistened foliage to dry quickly and helps prevent leaf diseases. Then wait to water again until the soil is dry to the touch. Some types of plants, such as cacti, as well as plants growing in low light levels may require watering just once a month. The most common reason that indoor plants fail to thrive is excessive watering, rather than neglect.
Houseplant Light Requirements
Indoor plants vary in their light requirements. Some thrive in low light levels, while others require a sunny window or the equivalent in artificial, full-spectrum grow lights. Plant labels should provide this information, or you can research the plants' light needs. Without adequate light, plants will become leggy and pale.
Houseplant Temperature and Humidity Requirements
Indoor temperatures of 55 to 70 degrees F. are usually adequate for most houseplants, though tropical emigrants such as holiday cactus and gardenia need cooler temperatures (60 to 65 degrees F.) to set buds. However, avoid placing plants near drafty doors, uninsulated windows, and heat sources. If you need to transport houseplants in cold weather, be sure to warm up the car first, wrap the plants in plastic bags, and get them into the car as quickly as possible. Even brief exposure to freezing temperatures can damage some tropical plants.
Many houseplant species are native to tropical rain forests and therefore are accustomed to high year-round humidity. Natural humidity levels in spring, summer, and fall are usually adequate. However, plants may require more moisture in winter, when heated indoor air dries out. A humidifier placed near the plants can help. Or, you can group the plants together on a layer of pebbles in a shallow basin or tray. Add water, to the basin, making sure the water level stays below the bottom of the pots. The closely spaced plants and the evaporating water help keep the humidity high. Misting plants provides only temporary moisture and doesn't significantly alter the overall humidity levels.
Fertilizing Houseplants
The best fertilizer for most flowering houseplants is a timed-release one that supplies nutrients to the plant every time you water. Complete fertilizers for houseplants work well; apply fertilizer twice monthly in spring and summer. If you use a water-soluble fertilizer, be sure to mix it according to label directions. A too-concentrated solution can harm plant roots. Once a month, flush the pots for a few minutes until water drains from the holes to remove any built-up fertilizer salts.
Houseplant Pests and Diseases
If you move plants outdoors in summer, chances are they'll pick up some insects. Before bringing them indoors, inspect plants carefully. The most common houseplant pests are mealybugs, aphids, spider mites, and scale; these can be controlled with insecticidal soap or horticultural oil.
To Save or Not to Save?
Holiday plants, such as poinsettias and cyclamen, can be challenging to keep alive much past the holidays. You can certainly give it a try, but don't feel bad if the plants begin to decline. Replace them with more adaptable types of indoor plants and you'll be able to enjoy your indoor garden year-round.
